The FEIS, issued for public comment in September 2013, assesses the potential transportation and environmental impacts and benefits of the Purple Line Preferred Alternative and the No Build Alternative.

"This announcement, coupled with the FTA's recommendation for funding earlier this month, moves the Purple Line one step closer to construction," said Maryland Gov. Martin O'Malley. "The Purple Line is another great example of our efforts to invest in our critical infrastructure, reducing congestion, improving our environment and driving transit ridership."

The FTA's Record of Decision marks the end of an extensive process to identify and then avoid, minimize or mitigate possible impacts to communities, historic buildings and natural resources such as parks, wetlands, streams and trees.

Now that the FTA has approved the FEIS and has recommended the project be partially financed through a Full Funding Grant Agreement, the MTA can move into the next phase of the project, which includes selecting a private partner to finalize design, build, finance, operate and maintain the project. Currently, MTA is working with four private-sector teams, who will submit proposals through a competitive process this year. In late 2014 or early 2015, MTA will select a preferred partner and recommend the final agreement to the Board of Public Works for its review and approval. Construction is planned to begin in 2015, with the line operational in late 2020.

The Purple Line is a 16-mile light-rail line that runs east-west inside the Capital Beltway between Bethesda in Montgomery County and New Carrollton in Prince George's County with 21 stations planned that will provide direct connections to Metrorail's Orange Line, Green Line and two branches of the Red Line and the MARC Brunswick, Camden and Penn Lines. Estimated ridership by 2040 is expected to be more than 74,000 and construction is estimated to create 6,300 regional jobs during the five-year construction period.

The total project cost is $2.371 billion, with the private sector expected to invest between $500 and $900 million. A combination of federal, state and local monies also will be used to fund the project.